Para-diisopropylbenzene is a valuable organic chemical compound that is currently used on a large scale industrially in the production of para-dihydroxybenzene (hydroquinone) and other aromatic compounds. Para-diisopropylbenzene can be produced by a number of different chemical processes. One such process that has achieved a significant degree of commercial success involves the alkylation of cumene with propylene in the presence of an alkylation catalyst. This alkylation process produces a mixture of para-diisopropylbenzene and meta-diisopropylbenzene. The alkylation catalyst used is selected to preferentially produce para-diisopropylbenzene. However, in commercial practice the alkylation still produces a diisopropylbenzene monomer mixture containing about 25 percent meta-diisopropylbenzene (based upon total diisopropylbenzene isomers) as an unwanted by-product.
In commercial practice the unwanted meta-diisopropylbenzene is reacted with benzene in a transalkylation reaction to produce cumene which is recycled back to the alkylation step. This commercial process of the prior art can be depicted as follows:

In this prior art process the para-diisopropylbenzene is separated from the meta-diisopropyl benzene by fractional distillation and collected as the desired product of the reaction. The undesired meta-diisopropylbenzene is transalkylated with benzene to produce cumene with is recycled back to the alkylation step. As can be seen, the prior art process calls for cumene, propylene, and benzene as raw materials. However, it would be highly desirable to eliminate benzene from the process. This is because it would no longer be necessary to purchase and store it for use in the synthesis of para-diisopropylbenzene benzene. The elimination of benzene from the synthesis process is of particular value since the use of benzene in industrial applications has been under attack on the basis of environmental, safety, and health concerns.